Software that can print a musical score from a piece of music or picks apart the sounds on a CD is being developed at DIT. Yvonne Cunninghamreports.
Researchers at the Dublin Institute of Technology have come up with a tool that can separate an ordinary CD track back into the sounds of its original instruments.
"The tool allows you to take a CD and extract any given instrument," says Dan Barry, a senior researcher and lecturer in the Department of Control Systems and Electrical Engineering at DIT.
"So if you have some jazz music you could extract just the saxophone or drums or bass and listen to that on its own. You can go back to what the individual tracks in the studio were before they got mixed in."
The sound separation tool works by using an algorithm which can tell where a recorded sound came from by its frequencies.
"It bases the separation on where the physical instrument is in space when the recording is being made. The path length from the instrument to the mike is different for each instrument and we do that computation 2,800 times," says Barry. "You can get about 100 frequency components from one direction."
There are other possible uses for the software. "This tool could work for satellites and biomedical applications," says Barry. "Another application is for mobile phones, to cut out background noise when you are using a mobile in a noisy place like a pub."
IF A SECOND microphone is added to a mobile phone, an algorithm could carry out a complex set of calculations, involving factors like the tiny time delay between a signal reaching the first and the second microphones.
"The results of these calculations could be used to determine which of the many noises being received on the microphones is the mobile user's voice. That signal can then be boosted and others frozen out," says Barry.
This research began as part of a Science Foundation Ireland-funded project called Digital Tools for Music Education, which developed tools for teachers and students of music.
The researchers working on the original project formed the audio research group. "We formed the group and we wrote further funding proposals, we're now working on about five other projects," says Barry. "Our main funding is from Enterprise Ireland and the EU's Framework 6 programme."
In one of these projects, DIT researchers are developing a tool which will help students to learn a piece of music.
"This tool takes a standard audio CD, analyses it and converts it to a notated score, it is still in development but it was released for accessing sound archives. It is used for historical archives to access the audio and view transcriptions," says Barry.
Another music project is a tool to allow musicians vary the speed of a piece of music, without changing the pitch.
"This is a tool to let musicians speed up and slow down music but not change the pitch - so you don't get the chipmunk effect. We developed an algorithm that can independently change the tempo of an audio recording without changing the pitch," says Barry.
"The tool can also allow you to change the key of a recording without changing the tempo," he adds. This is a useful learning aid for students, who can slow down a piece of music if they can't keep up.